Limits...
Role of p75 neurotrophin receptor in the neurotoxicity by beta-amyloid peptides and synergistic effect of inflammatory cytokines.

Perini G, Della-Bianca V, Politi V, Della Valle G, Dal-Pra I, Rossi F, Armato U - J. Exp. Med. (2002)

Bottom Line: This signaling leads to the activation of caspases-8 and -3, the production of reactive oxygen intermediates and the induction of an oxidative stress.In fact, TNF-alpha and IL-1beta, cytokines produced by Abeta-activated microglia, could potentiate the neurotoxic action of Abeta mediated by p75(NTR) signaling.Together, our results indicate that neurons expressing p75(NTR), mostly if expressing also proinflammatory cytokine receptors, might be preferential targets of the cytotoxic action of Abeta in AD.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Bologna, Via Selmi 3, 40126 Bologna, Italy.

ABSTRACT
The neurodegenerative changes in Alzheimer's disease (AD) are elicited by the accumulation of beta-amyloid peptides (Abeta), which damage neurons either directly by interacting with components of the cell surface to trigger cell death signaling or indirectly by activating astrocytes and microglia to produce inflammatory mediators. It has been recently proposed that the p75 neurotrophin receptor (p75(NTR)) is responsible for neuronal damage by interacting with Abeta. By using neuroblastoma cell clones lacking the expression of all neurotrophin receptors or engineered to express full-length or various truncated forms of p75(NTR), we could show that p75(NTR) is involved in the direct signaling of cell death by Abeta via the function of its death domain. This signaling leads to the activation of caspases-8 and -3, the production of reactive oxygen intermediates and the induction of an oxidative stress. We also found that the direct and indirect (inflammatory) mechanisms of neuronal damage by Abeta could act synergistically. In fact, TNF-alpha and IL-1beta, cytokines produced by Abeta-activated microglia, could potentiate the neurotoxic action of Abeta mediated by p75(NTR) signaling. Together, our results indicate that neurons expressing p75(NTR), mostly if expressing also proinflammatory cytokine receptors, might be preferential targets of the cytotoxic action of Abeta in AD.

Show MeSH

Related in: MedlinePlus

Expression of p75NTR in SK-N-BE neuroblastoma clones. (A) Schematic depiction of the full-length and truncated p75NTR proteins expressed in transfected SK-N-BE clones. Specifically, p75NTR, full-length receptor; p75ΔECD, p75 lacking the extracellular region (aa 36–230); p75ΔICD, p75 lacking the whole cytoplasmatic region (aa 280–427); p75ΔDD, p75 lacking the intracellular DD (aa 352–427); p75ΔJICD, p75 lacking the cytoplasmic JICD (aa 275–340). TM, transmembrane region. (B) p75NTR protein levels (Western blot analysis) in BENTR-free cell clones transfected with different constructs of p75NTR. (C) Localization of the p75NTR protein at the plasmamembrane by immunostaining with 9992 antiserum in BENTR-free, BEp75, BEp75ΔECD, BEp75ΔDD, and BEp75ΔJICD cell clones, and with mAb ME20.4 in BEp75ΔICD cell clones; the detection was performed by Cy3-conjugated anti–rabbit IgG or anti–mouse IgG; nuclei are blue-stained with DAPI.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2193732&req=5

fig1: Expression of p75NTR in SK-N-BE neuroblastoma clones. (A) Schematic depiction of the full-length and truncated p75NTR proteins expressed in transfected SK-N-BE clones. Specifically, p75NTR, full-length receptor; p75ΔECD, p75 lacking the extracellular region (aa 36–230); p75ΔICD, p75 lacking the whole cytoplasmatic region (aa 280–427); p75ΔDD, p75 lacking the intracellular DD (aa 352–427); p75ΔJICD, p75 lacking the cytoplasmic JICD (aa 275–340). TM, transmembrane region. (B) p75NTR protein levels (Western blot analysis) in BENTR-free cell clones transfected with different constructs of p75NTR. (C) Localization of the p75NTR protein at the plasmamembrane by immunostaining with 9992 antiserum in BENTR-free, BEp75, BEp75ΔECD, BEp75ΔDD, and BEp75ΔJICD cell clones, and with mAb ME20.4 in BEp75ΔICD cell clones; the detection was performed by Cy3-conjugated anti–rabbit IgG or anti–mouse IgG; nuclei are blue-stained with DAPI.

Mentions: The construct encoding for the wild-type (wt) p75NTR (pCEP4β-p75) was generated by cloning the full-length human p75NTR cDNA into the PvuII site of the pCEP4β mammalian expression vector which carries the hygro resistance gene (see Fig 1 A; Invitrogen). The p75ΔDD mutant, lacking aa from 352 to 427, was generated according to Hantzopoulos (53). The other deletion mutants p75ΔECD, p75ΔICD, and p75ΔJICD were obtained by PCR using specific primers and cloning the respective products into the pCEP4β vector. Tropomyosin-related kinase (Trk)A expression plasmid was obtained by inserting the full-length cDNA encoding for the human TrkA receptor (54) into the episomal expression vector pCEP9β which carries the neo resistance gene.


Role of p75 neurotrophin receptor in the neurotoxicity by beta-amyloid peptides and synergistic effect of inflammatory cytokines.

Perini G, Della-Bianca V, Politi V, Della Valle G, Dal-Pra I, Rossi F, Armato U - J. Exp. Med. (2002)

Expression of p75NTR in SK-N-BE neuroblastoma clones. (A) Schematic depiction of the full-length and truncated p75NTR proteins expressed in transfected SK-N-BE clones. Specifically, p75NTR, full-length receptor; p75ΔECD, p75 lacking the extracellular region (aa 36–230); p75ΔICD, p75 lacking the whole cytoplasmatic region (aa 280–427); p75ΔDD, p75 lacking the intracellular DD (aa 352–427); p75ΔJICD, p75 lacking the cytoplasmic JICD (aa 275–340). TM, transmembrane region. (B) p75NTR protein levels (Western blot analysis) in BENTR-free cell clones transfected with different constructs of p75NTR. (C) Localization of the p75NTR protein at the plasmamembrane by immunostaining with 9992 antiserum in BENTR-free, BEp75, BEp75ΔECD, BEp75ΔDD, and BEp75ΔJICD cell clones, and with mAb ME20.4 in BEp75ΔICD cell clones; the detection was performed by Cy3-conjugated anti–rabbit IgG or anti–mouse IgG; nuclei are blue-stained with DAPI.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2193732&req=5

fig1: Expression of p75NTR in SK-N-BE neuroblastoma clones. (A) Schematic depiction of the full-length and truncated p75NTR proteins expressed in transfected SK-N-BE clones. Specifically, p75NTR, full-length receptor; p75ΔECD, p75 lacking the extracellular region (aa 36–230); p75ΔICD, p75 lacking the whole cytoplasmatic region (aa 280–427); p75ΔDD, p75 lacking the intracellular DD (aa 352–427); p75ΔJICD, p75 lacking the cytoplasmic JICD (aa 275–340). TM, transmembrane region. (B) p75NTR protein levels (Western blot analysis) in BENTR-free cell clones transfected with different constructs of p75NTR. (C) Localization of the p75NTR protein at the plasmamembrane by immunostaining with 9992 antiserum in BENTR-free, BEp75, BEp75ΔECD, BEp75ΔDD, and BEp75ΔJICD cell clones, and with mAb ME20.4 in BEp75ΔICD cell clones; the detection was performed by Cy3-conjugated anti–rabbit IgG or anti–mouse IgG; nuclei are blue-stained with DAPI.
Mentions: The construct encoding for the wild-type (wt) p75NTR (pCEP4β-p75) was generated by cloning the full-length human p75NTR cDNA into the PvuII site of the pCEP4β mammalian expression vector which carries the hygro resistance gene (see Fig 1 A; Invitrogen). The p75ΔDD mutant, lacking aa from 352 to 427, was generated according to Hantzopoulos (53). The other deletion mutants p75ΔECD, p75ΔICD, and p75ΔJICD were obtained by PCR using specific primers and cloning the respective products into the pCEP4β vector. Tropomyosin-related kinase (Trk)A expression plasmid was obtained by inserting the full-length cDNA encoding for the human TrkA receptor (54) into the episomal expression vector pCEP9β which carries the neo resistance gene.

Bottom Line: This signaling leads to the activation of caspases-8 and -3, the production of reactive oxygen intermediates and the induction of an oxidative stress.In fact, TNF-alpha and IL-1beta, cytokines produced by Abeta-activated microglia, could potentiate the neurotoxic action of Abeta mediated by p75(NTR) signaling.Together, our results indicate that neurons expressing p75(NTR), mostly if expressing also proinflammatory cytokine receptors, might be preferential targets of the cytotoxic action of Abeta in AD.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Bologna, Via Selmi 3, 40126 Bologna, Italy.

ABSTRACT
The neurodegenerative changes in Alzheimer's disease (AD) are elicited by the accumulation of beta-amyloid peptides (Abeta), which damage neurons either directly by interacting with components of the cell surface to trigger cell death signaling or indirectly by activating astrocytes and microglia to produce inflammatory mediators. It has been recently proposed that the p75 neurotrophin receptor (p75(NTR)) is responsible for neuronal damage by interacting with Abeta. By using neuroblastoma cell clones lacking the expression of all neurotrophin receptors or engineered to express full-length or various truncated forms of p75(NTR), we could show that p75(NTR) is involved in the direct signaling of cell death by Abeta via the function of its death domain. This signaling leads to the activation of caspases-8 and -3, the production of reactive oxygen intermediates and the induction of an oxidative stress. We also found that the direct and indirect (inflammatory) mechanisms of neuronal damage by Abeta could act synergistically. In fact, TNF-alpha and IL-1beta, cytokines produced by Abeta-activated microglia, could potentiate the neurotoxic action of Abeta mediated by p75(NTR) signaling. Together, our results indicate that neurons expressing p75(NTR), mostly if expressing also proinflammatory cytokine receptors, might be preferential targets of the cytotoxic action of Abeta in AD.

Show MeSH
Related in: MedlinePlus